Venetian blind slat



Jan. 16, 1940. T. A. GRAVES 2,187,121 vENETiAN BLIND SLAT Filed Feb. 23,1938 2 Sheets-Sheet 1 Jan. 16, 1940. T. A. GRAVES VENETIAN BLIND SLATFiled Feb. 2a, 1938 2 Sheeis-Sheet 2 IN VEN TOR.-

- BY M 7 7ATT0RNEY Patented Jan. 16, 1940 um'nezb STATES PATENT OFFICEVENETIAN BLIND SLAT Application February 23, 1938, Serial No. 191,911

6 Claims.

This invention relates to Venetian blinds and more particularly totranslucent or semi-transparent Venetian blind slats which are made fromflexible sheet material'without stitching.

There are two distinct types of window shades commonly used at thepresent time one of which is the ordinary window shade which is preparedfrom coated fabrics and mounted on a spring roller, and the other ofwhich is the Venetian blind type which consists of a plurality ofindividual horizontal slats uniformly spaced and suspended on verticalstrips which may be raised or lowered by suitable elevator cords. Theformer of these two types has been in use to a considerable extent dueto its lower cost, but has the disadvantage that during the daytime itshuts out all direct light although recently translucent shade cloth hasbeen made available commercially.

Heretofore, Venetian blind slats have been made of wood or metal andwhile they add considerable charm: and distinction to a room, they donot-have the property of transmitting diffused light when the slats areadjusted to the as closed position.

It has been proposed therefore to use coated fabrics in the constructionof slats for blinds of this type and the usual method of doing this isto stitch the fabric in a manner such that a longitudinal pocket isproduced and a metal frame is inserted into the pocket and then theclosing flap either stitched or otherwise suitably closed. The slatsprepared in such a manner are easily twisted out of shape, and it isthis disadsince slats which have become twisted 'lose the beauty oftheir symmetrical lines and then have a very unsightly appearance.

It is an object of the presentyinvention to o produce a Venetian blindslat which has no stitching and which may be made of flexible,translucent material having sufficient rigidity to maintain a flatcondition in use.

Another object is the provision of a nonstitched cloth Venetian blindslat with a substantially plain surface on one side.

Other objects will be apparent as the description of the inventionproceeds.

. The foregoing objects are accomplished by preparing a Venetian blindslat which comprises a flexible translucent or semi-transparent fabricsupported by metal reinforcing elements, the

edges of the fabric being bonded to the metala by means of an adhesivein such a'manner that vantage which the present invention overcomes themetal may be considered as being embedded in a mass of the adhesive. Inthe drawings, the successive figures show the method of preparing a slatin accordance with this invention. Figure 1 is a plan view of a flexiblesheet material which forms the body of a slat and which has been cut tothe desired shape. Figure 2A is a plan view showing a blanking outelement centered on the sheet on which adhesive has been applied to theportion not blanked out. Figure 2 is a plan view of the .fabric afterthe blanking out element has been removed. Figure 3 is a plan viewshowing the steel frame in place. Figure 4 is a plan view showing thelongitudinal edges of the sheet material folded over the steel frame.Figure 5 is .a plan view showing all of the edges folded over the steelframe. Figure 5A is a top plan view with an end in section. Figure 6 isa section along the line 6-6 of Figure 5. Figures 7 and l1-A areimaginary sections along the line 6-6 where a modification has been usedin winding the fabric around the metal frame 1% times and 1 times,respectively. Figures 13 and 14 are transverse reinforcing elements.Figures 8 and 10 are plan'views of the opposite sides of a slat showingthe reinforcing elements in place other than at the ends. Figure 9 is aplan view of a slat which has been distorted. Figure 10 has reinforcingelements also at the end.

Figure 8 A represents a plan view of a slat in which the reenforcementsrunning transversely are welded to those running longitudinally.

Figure l0A likewise is a plan view of a slat in which clips, shown indetail in Figure 13, are .used. Figure 11 is a plan view similar toFigure l0A but is broken to show a section and also shows the endreenforcements eliminated. Figure 12 is a portion of a plan view of aslat showing the combination of the clip shown in Figure 14 and an endreenforcement which is clamped in -place rather than being integral withthe longitudinal reenforcing members.

A slat prepared according to the prior art will remain in this position,while a slat prepared according to the present invention will return tothe position shown in Figure 5A, upon the removal of the distortingforce. Figure 10-A is a plan view of the opposite side of the slat fromthat shown in Figure 10 with one end in section. Figure 14 is a detailplan view of a portion of a modification in which the slat is likeFigure 11 with a crimpedreinforcing element at the end.

In all the figures, i represents the coated faba ric, 2 indicatesopenings through which the elevator cords may pass. The adhesive isindicated as 3, and the metal reinforcing member as 4. The transversereinforcing members are shown as I and 9. In the latter, two of the ears5 are pressed over the rod 4 and one ear [0 is pressed under the rod.Figure 14 is a detailed view of member 9.

According to the present invitation, the slats are made by cutting asuitably shaped piece of fabric which may be coated or uncoated in thegeneral shape as shown in Figure 1. In the preferred embodiment, thefabric is coated with pyroxylin. This may be done by coating it with adoctor knife. A suitable fabric has been found to be one having a threadcount of 68 x 72 and weighing 3.1 ozs. per square yard. This material isthen coated with a composition having the following formula:

Percent by weight Cellulose nitrate 15.1

Dibutyl phthalate 12.5 Bone black 0.7 Leaded zinc oxide f. 22.5 Chromeyellow 0.9 Chrome orange 0.9 Ethyl acetate 19.0 Ethyl alcohol 28.4

Four coats of this composition are applied which produces a light browntranslucent window shade material.

In one embodiment of the invention, this fabric is die-cut to the shapeshown in Figure 1 so that when the edges are folded over they will bebutted at the corners as shown in Figure 5. The.

openings 2 are also cut in the fabric to permit the raising and loweringof the blind by means of elevator cords. After the material has beencut, a blanking out member 20, as shown in Figure 2A is placed on thesheet and adhesive is applied by brushing, spraying, or any othersuitable method to the exposed area as shown at 3.

The adhesive may be of any type depending on the fabric or paper ofwhich the slat is constructed. With fabrics coated with pyroxylin it hasbeen found that a cellulose nitrate cement having approximately thefollowing formula is particularly satisfactory:

Per cent Cellulose nitrate 12.35 Ethyl alcohol 43.82 Ethyl acetate 43.83

After the adhesive has been applied and before it dries, a metalrectangular frame 4 is placed on the adhesive as shown in Figure 3. Themetal frame may be constructed of rigid or hollow steel. It has beenfound that No. 13 gauge spring steel is particularly satisfactoryalthough variations in this reinforcing member will be obvious to tionis primarily a hand operation and is given to illustrate the principleof the invention more clearly. It does not lend itself, however, tolarge scale production and in the commercial manufacture of slatsprepared according to the present invention, a slightly modifiedembodiment of the invention is used. This embodiment is a twostepoperation. The first of these steps is the preparation of the pyroxylincoated fabric and X the slicing of it into strips approximately 2 x 1'inches wide. The coated fabric is then rolled up into large rolls.Either before or simultaneously with the rolling up of the fabric, anadhesive is applied to the edges which may be thermoplastic in nature orone which dries to'a non-tacky condition and which is activated withsolvent in the second step of the operation. If a thermoplastic cementis used, heat and pressure are applied instead of the solvent toactivate the cement.

The second step of the operation involves passing the strip of fabricand the longitudinal metal reinforcing rods into an automatic machinewhich holds the rods a fixed distance apart, turns the edges of thefabric over the rod, and either applies solvent or heat to activate thecement depending on whether or not it is thermoplastic. Before thesemi-finished slat leaves the machine, it is cut into suitable lengthsdepending on the width of the window on which the finished blind is tobe used. When the slat is made on such an automatic machine, it has beenfound that an end reinforcing member shown as 8 in Figure 12 simplifiesthe operation. It has also been found that a clip such as that shown inFigure 14 may easily be attached to the slat. It is to be understoodthat the machine attaches the end reinforcing member as well as thetransverse reinforcing element. The holes for the elevator cords may bestamped out of the fabric before or while it passes through the machine.

The manner in which the adhesive welds or bonds the coated fabric to themetal frame is not to be confused with the use of an adhesive as asubstitute for stitching confined to the limited area ordinarilystitched together. In the present invention, the metal is embedded in amass of adhesive which firmly bonds the metal to the coating on thefabric which in turn extends into its interstices, thereby forming anextremely rigid and integral unit.

The slat made as indicated above may be used in the ladder tape so thatthe substantially plane surface of the slat is up when it is adjusted toa horizontal position. It is very important that the fabric be securelybonded throughout to the metal frame since this results in greatresistance to the torque of a distorting force. In the case of prior artslats, if the metal frame is enclosed in a pocket or hem formed by a rowof stitching, they may be distorted very easily since the metal isallowed to twist within the pocket and when the distorting force isremoved such slats do not return to their original shape. Slats madeaccording to the present invention do not have this drawback and readilyreturn to a fiat condition when the distorting force is removed.

In order to demonstrate the resistance of the slats of the presentinvention to the torque of a distorting force, they may be compared tothose prepared by stitching by laying both on a table top and applying avertical lifting force at one corner of each slat with the remaininglongitudinal edge in contact with the table top. It will be found thatthe prior art stitched slat will be twisted out of shape until it isforced back again, whereas material made according to the presentinvention will return to its original position quickly.

It is usually preferred to use a pyroxylin coated fabric in makingslats; however, paper such as flfty pound Alpha paper which is used inthe production of paper window shades, may be used. This material isalso coated with pyroxylin in a manner similar to that indicated abovefor cloth. It is also possible to use uncoated paper which may becolored in any desired design.

Where the translucent property of the slats is not desired, opaquematerials may be used to form the covering material for the metalframe-. work. The location of the transverse portion of the metalframework is immaterial and it may be at the ends as shown in Figure 5,or located as shown in Figures 8 and 8-A near the elevator cordopenings. A transverse reinforcing element may also be applied to theoutside of the flexible sheet material as shown in Figures 10 and 10-A,and this may be in addition to or in lieu of the transverse member atthe end as shown in Fig- Any surface within reasonable limits may beobtained by varying the composition applied, and surfaces having a dullfinish or a high gloss are readily obtainable, depending on therequirements for which the slat is to be used. The main advantage ofslats according to the present invention is that they lie insubstantially a plane surface on the top side.

It is apparent that many widely different embodiments of this inventionmay be made without departing from the spirit and scope thereof; and,

therefore, it is not intended to be limited except as indicated in theappended claims.

I claim:

1. A Venetian blind slat comprising a flexible fabric having a metalreinforcing member about its periphery embedded in a mass of adhesive.

2. Product of claim 1 in which the adhesive is a cellulose derivative.cement.

3. Product of claim 1 in which the fabric is coated with anitrocellulose composition.

4. A Venetian blind slat comprising a flexible pyroxylin coated fabrichaving a metal reinforcing member passing around its periphery, the saidfabric being securely bonded to the metal by means of a substantial massof cellulose derivative composition.

5. Process of preparing Venetian blind slats which comprises cutting outa blank from a cellulose derivative coated composition in the form of anoctagon in which two of the parallel sides are many times the length ofthe sides perpendicular thereto, coating the outer edge of the saidblank with a cellulose derivative cement, placing a rectangularreinforcing member on the cement, folding over the outer edges wherebythe reinforcing member is embedded in a matrix of the cement.

6. The process of preparing Venetian blind slats which comprisespreparing a long strip of pyroxylin coated fabric, coating the edges ofthe said strip with a cement, placing two parallel longitudinalreinforcing members on the strip of fabric in contact with the cement,turning the edges of the strip over the longitudinal member,

activating the. cement, applying pressure to join the folded portionwith the main portion of the fabric, cutting off suitable lengths of thematerial so prepared, and crimping transverse reinforcing members overthe ends of the slat.

THOMAS A. GRAVES.

